Conventionally, in the pharmaceutical industry and other fields, preparative separation/purification systems utilizing chromatographs are used to analyze synthesized compounds or store them in a library (Refer to Japanese Unexamined Patent Application Publication No. H02-122260).
In these apparatuses, target components (compounds) in a sample solution are temporally separated by a liquid chromatograph. The separated target components are then respectively introduced into different trap columns and temporarily captured therein. Subsequently, a solvent is supplied into each trap column to quickly elute the component from the trap column and collect it in a container. Thus, a plurality of solutions each containing one target component at a high concentration are collected in respective containers. These separately collected solutions are then subjected to a vaporizing and drying process to remove the solvent and collect the target components in solid forms. The vaporizing and drying process normally includes heating the collected eluate or centrifuging them under a vacuum.
According to the aforementioned method, however, a single vaporizing and drying process requires a long period of time of for example, several hours to one day. In the pharmaceutical industry, various efforts have been made to improve the efficiency of searching for a large number of synthetic compounds for medicinal compounds; for example, the analysis time has been reduced by using faster analysis apparatuses or optimizing the analytical methods. Reducing the time required for the vaporizing and drying process is a critical issue since this process consumes, within the entire process, the longest period of time.
One reason that a long period of time is required to vaporize the solvent from the eluate collected is the presence of water included in the collected eluate. As the solvent for eluting target components captured in a trap column, an organic solvent is often used. As compared to water, organic solvents have much lower boiling points and hence are highly volatile. Therefore, when the target components are dissolved in a pure organic solvent, the vaporizing and drying process requires only a short period of time. On the other hand, if water, which is less volatile, is included in the solvent, the vaporizing and drying process takes a considerably longer period of time.
When the target component is introduced into the trap column with the mobile phase and captured therein, in many cases, the mobile phase consists of either water or an aqueous solvent containing water as the main component. In these cases, a certain amount of water remains in the trap column at the completion of capturing the target component. This problem also arises in the widely used technique of introducing water into the passage of the mobile phase at a location before the trap column in order to dilute the mobile phase with water and thereby reduce the elution power of the mobile phase so that the target component can be assuredly captured. In this case, the water remains in the trap column at the completion of capturing the target component. Furthermore, after the target component is captured, it is often necessary to wash the trap column by introducing water into it to remove unnecessary components other than the target one, such as the salts originating from the mobile phase, that are present within the trap column. In this case, the mobile phase in the trap column is replaced with water, so that the trap column becomes filled with the water.
For such a variety of reasons, in many cases, the trap column contains a considerable amount of water after the target component is captured. When such a large amount of water is present in the trap column, supplying an organic solvent into the trap column to elute the target component will naturally result in a large amount of remnant water to be included in the solution exiting from the trap column. If both water and an organic solvent are contained in the collected solution, a long period of time is required to vaporize the water, and what is worse, the water overlies the organic solvent stored in the collection container as a cover, which prevents the organic solvent from evaporating.
To solve this problem, a preparative separation/purification system has been developed which is capable of removing water and other unwanted residual solvents from a trap column in a short period of time before a target component captured in a trap column is eluted from the column (International Publication No. WO2009/044426). In this preparative separation/purification system, a second solvent is supplied from the lower end of the trap column, with the target component held in the trap column. The second solvent has a specific gravity greater than the specific gravity of a first solvent (water or an aqueous solvent) remaining in the trap column and has a low solubility to the first solvent. Consequently, the first solvent is pushed up by the second solvent and discharged from the trap column. By disposing of this first solvent, the first solvent is removed from the trap column. In this manner, the preparative separation/purification system of International Publication No. WO2009/044426 can collect an eluate consisting of a water-free organic solvent with the target component dissolved therein. Hence, the solvent in this eluate can be vaporized in a short period of time to obtain the target component in dry, solid forms.